Weird behavior HP41c

[Neve]

Hi all,

I had this weird message when I clicked on the PRGM key on my Tall-Key HP41C this morning.
I was greeted with just “PRIVATE”. I suspect something is wrong with the logic board as I sometimes get “NONEXISTENT” when I try to clear a program that I know should be there.
Sometimes that same program lists in CAT 1 and sometimes it doesn’t. Sometimes, when I have 3 or 4 programs in memory, they all disappear. Hummmm...
Anyways, this one is my #1 candidate for the new V5 CL board. If nothing else is wrong, the new board should take care of that.
Though I’m still curious as to what the experts think. Are these different issues? Are they related? What could be the cause? Worthy to note that I have a QUAD MEMORY module plugged in. Maybe it is the culprit....

Thanks

[Geoff Quickfall]

Memory curtain has shifted. So some of your programs are now partitioned on the wrong side of the memory map.

The dreaded electrostatic discharge that the 41 is famous for. What happens on CAT 1? Have programs disappeare? Do you have a single .END? Weird CAT 1 program listings and characters?

Encountered this a million times when experimenting with Synthetic programming. Actually moved phone number program into the private domain and back again using synthetic commands.

So a memory lost is required then a reboot with whatever you use to reprogram!

Card reader

Tape drive

Floppy drive

Laser Wand

FINGERS...

CHEERS, geoff

[Neve]

(10-02-2017 06:15 AM)Geoff Quickfall Wrote:  Memory curtain has shifted. So some of your programs are now partitioned on the wrong side of the memory map.

The dreaded electrostatic discharge that the 41 is famous for. What happens on CAT 1? Have programs disappeare? Do you have a single .END? Weird CAT 1 program listings and characters?

Encountered this a million times when experimenting with Synthetic programming. Actually moved phone number program into the private domain and back again using synthetic commands.

So a memory lost is required then a reboot with whatever you use to reprogram!

Card reader

Tape drive

Floppy drive

Laser Wand

FINGERS...

CHEERS, geoff

I didn’t understand everything you wrote, but I’ve done a MEMORY LOST several times.
It still comes up every once in a while.
Yes, I get just one .END in CAT 1.
The “PRIVATE” thing when hitting PRGM is a first though.
I’ve never done any synthetic programming other than loading the Byte Grabber.
I may have messed around with it and did something wrong...
Other than a MEMORY LOST, I don’t know what you mean by “reboot”.

[Geoff Quickfall]

Reboot, on+clear reset ie. induced memory lost.

Your Memory curtainposiyion is corrupted.

since a Memory Loss reset did not work Google "resetting frozen HP 41."

How too...

HP museum rest instructions

And many more.

Let us know.

P.s.

1) induce memory loss with key sequence clear+on

2) remove batteries, then short the farthest left and right battery contacts to discharge continuous memory capacitor.

3) insert batteries in wrong direction in battery pack. Insert pack and turn on machine and immediately remove battery pack. (You can skip this if sqeamish).

4) remove battery pack for a few days to discharge memory capacitor.

5) ensure all connections are clean.

6) ensure case is structurally sound( no cracked or loose screws posts.

[Neve]

(10-02-2017 06:55 AM)Geoff Quickfall Wrote:  Reboot, on+clear reset ie. induced memory lost.

Your Memory curtainposiyion is corrupted.

since a Memory Loss reset did not work Google "resetting frozen HP 41."

How too...

HP museum rest instructions

And many more.

Let us know.

P.s.

1) induce memory loss with key sequence clear+on

2) remove batteries, then short the farthest left and right battery contacts to discharge continuous memory capacitor.

3) insert batteries in wrong direction in battery pack. Insert pack and turn on machine and immediately remove battery pack. (You can skip this if sqeamish).

4) remove battery pack for a few days to discharge memory capacitor.

5) ensure all connections are clean.

6) ensure case is structurally sound( no cracked or loose screws posts.

Thanks! Will read all this carefully and report back in a few...

[Neve]

Hi again,

Neither shorting the battery contacts nor the inverted batteries method induce a MEMORY LOSS on this machine. The only thing that does that is the on/clear sequence. Or, of course, removing the Quad Memory module.

Now, I don’t know if this is gonna help since this behavior doesn’t happen all the time.
It’s pretty sporadic and unexpected, and of course very annoying.

PS-1: I used almost totally drained inverted batteries (0.300v each approx).
PS-2:This machine doesn’t suffer from broken posts. The logic board is held in place by hex nuts that I have never removed.

[Geoff Quickfall]

Both shorting the extreme left to the extreme right battery contacts and the inverted batteries should induce Memory Lost.

Forget the inverted battery method .

I have in extreme cases left the batteries out of the calc for a week with a shorting clip attached to both battery connections mentioned above.

Your two PS's change the diagnosis. It now sounds like a RAM problem. Maybe a loose solder connection on one of the ram chips.

Caveat, the hex nuts were not made to come off and go back on. They self tap and end up cross threading the next time they are used. HP when repairing used spacers in place of the hex nuts.
Have you seen:

Donors for HP41CL

[Neve]

(10-02-2017 03:51 PM)Geoff Quickfall Wrote:  Both shorting the extreme left to the extreme right battery contacts and the inverted batteries should induce Memory Lost.

Forget the inverted battery method .

I have in extreme cases left the batteries out of the calc for a week with a shorting clip attached to both battery connections mentioned above.

Your two PS's change the diagnosis. It now sounds like a RAM problem. Maybe a loose solder connection on one of the ram chips.

Caveat, the hex nuts were not made to come off and go back on. They self tap and end up cross threading the next time they are used. HP when repairing used spacers in place of the hex nuts.
Have you seen:

Donors for HP41CL

Yes, I had seen the thread a while back.
Well, for some reason, on this machine, shorting the two outmost batterie contacts does absolutely nothing.
I even left a tin foil on all contacts for over an hour, and zilch....
All I can do is try longer and/or wait for the new CL board to be ready and ship out.
At least I have another one (fullnut CX) to play and work with at the moment.
However, it still works and displays all 319 registers with the Quad Memory module. Just that erratic behavior every now and then.

Thanks

[Geoff Quickfall]

Does it only happen when the quad is in place? Is the calc stable without the quad in place? If so maybe a contact problem on the module. Ensure contact springs in module (visible) are not deformed. Perhaps an intermittent contact causing the partition to corrupt when calc is jiggled.

I have placed a drop of DeOxit gold or Red on the contacts of the module then plug and unplug a few times.

[Neve]

(10-02-2017 04:45 PM)Geoff Quickfall Wrote:  Does it only happen when the quad is in place? Is the calc stable without the quad in place?

To be honest, I haven’t tried.

(10-02-2017 04:45 PM)Geoff Quickfall Wrote:  If so maybe a contact problem on the module. Ensure contact springs in module (visible) are not deformed. Perhaps an intermittent contact causing the partition to corrupt when calc is jiggled.

I have placed a drop of DeOxit gold or Red on the contacts of the module then plug and unplug a few times.

I’ll check that and use some contact cleaner if needed.

Thank You (Again...!)

[Neve]

(10-02-2017 06:55 AM)Geoff Quickfall Wrote:  Reboot, on+clear reset ie. induced memory lost.

Your Memory curtainposiyion is corrupted.

since a Memory Loss reset did not work Google "resetting frozen HP 41."

How too...

HP museum rest instructions

And many more.

Let us know.

P.s.

1) induce memory loss with key sequence clear+on

2) remove batteries, then short the farthest left and right battery contacts to discharge continuous memory capacitor.

3) insert batteries in wrong direction in battery pack. Insert pack and turn on machine and immediately remove battery pack. (You can skip this if sqeamish).

4) remove battery pack for a few days to discharge memory capacitor.

5) ensure all connections are clean.

6) ensure case is structurally sound( no cracked or loose screws posts.

Thanks! Will read all this carefully and report back in a few...